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Emails getting delayed/blocked on a few mail servers RRS feed

  • Question

  • Hello,

    We can send to thousands of email servers no problem but a few seem to be having an issue.     We can't seem to find any issues with our server with dnsstuff, we don't seem to be on any whitelists with mxlookup and our spf record appears to be valid.    I'm not sure what is wrong but if you can spot it, I would appreciate it.

    Remote Server at returned '441 4.4.1 Error
    encountered while communicating with primary target IP address: "Failed to
    connect. Winsock error code: 10060, Win32 error code: 10060." Attempted
    failover to alternate host, but that did not succeed. Either there are no
    alternate hosts, or delivery failed to all alternate hosts. The last endpoint
    attempted was
    Attempted failover to
    alternate host, but that did not succeed. Either there are no alternate hosts,
    or delivery failed to all alternate hosts. The last endpoint attempted was

    Turns out we have it with 3 clients who all have their email on serverdata.net.   We can't get in touch with serverdata.net.   


    • Edited by boe_d Friday, June 8, 2018 11:47 PM
    Friday, June 8, 2018 9:28 PM

All replies

  • Hello,

    We have an exchange 2013 CU20 server.   All of a sudden we are getting this error when sending to 2 clients.   We can ping their mx addresses but can't reliably telnet to them.   Once in a while we can telnet but if we do kill the telnet session and try again it can't' connect.   

    This is a new development

    I can't find our sending server IP on any blacklists.  

    We can send emails to almost everyone but these two domains.

    They can't figure out how to whitelist us.

    We can send them emails but they are delayed by several hours and we get a bounce back "'441 4.4.1 Error encountered while communicating with primary target IP address: "Failed to connect. Winsock error code: 10060, Win32 error code: 10060." "

    I checked our DNS it is fine.   I made the exchange server only use internal DNS - it was set for external but that had the same issue.  Our only nic on the server only has one internal IP and only uses our internal DNS server that does resolve the IP of their email server correctly every time.

    We can telnet to their email system from another system run by a colleague but not another.  

    The email system we can't send to is serverdata.net - we can't seem to get any support on the issue with their client.

    It seems odd that we can telnet at random periods but only one time.

    We have a static IP, A PTR and an SPF that have been in place for over a year - the issue just began.

    We do not have any software firewall on our server.   We are able to telnet to other servers when we can't to that one server.
    • Edited by boe_d Saturday, June 9, 2018 7:24 PM
    • Merged by Manu Meng Monday, June 11, 2018 8:33 AM duplicated thread
    Saturday, June 9, 2018 6:43 PM
  • Hello,

    We have an exchange 2013 CU20 server.   All of a sudden we are getting this error when sending to 2 clients.   We can ping their mx addresses but can't reliably telnet to them.   Once in a while we can telnet but if we do kill the telnet session and try again it can't' connect.   

    This is a new development

    I can't find our sending server IP on any blacklists.  

    We can send emails to almost everyone but these two domains.

    They can't figure out how to whitelist us.

    We can send them emails but they are delayed by several hours and we get a bounce back "'441 4.4.1 Error encountered while communicating with primary target IP address: "Failed to connect. Winsock error code: 10060, Win32 error code: 10060." "

    I checked our DNS it is fine.   I made the exchange server only use internal DNS - it was set for external but that had the same issue.  Our only nic on the server only has one internal IP and only uses our internal DNS server that does resolve the IP of their email server correctly every time.

    We can telnet to their email system from another system run by a colleague but not another.  

    The email system we can't send to is serverdata.net - we can't seem to get any support on the issue with their client.

    It seems odd that we can telnet at random periods but only one time.

    We have a static IP, A PTR and an SPF that have been in place for over a year - the issue just began.

    We do not have any software firewall on our server.   We are able to telnet to other servers when we can't to that one server.

    Have you asked them?

    Saturday, June 9, 2018 7:27 PM
  • Thanks for replying -

    Asked whom?

    If you are talking about serverdata.net the company hosting the system we can't send to - no.  They don't want to deal with us directly.  The IT company that supports the end user that has their domains email on the dataserver.net system has been in touch with them.   We've send them the bounce back messages, we've sent them screen shots of the telnet not connecting but the ping responding, we've send them times when we can send, times when we can't.   We've sent them our smtp send connector log.   They still keep on asking for more logs.   They think it is a TLS issue but I'm not sure what TLS has to do with anything when sometimes we can telnet and sometimes we can't.   Does Telnet use some sort of tls that might vary?


    • Edited by boe_d Saturday, June 9, 2018 7:42 PM
    Saturday, June 9, 2018 7:37 PM
  • Thanks for replying -

    Asked whom?

    If you are talking about serverdata.net the company hosting the system we can't send to - no.  They don't want to deal with us directly.  The IT company that supports the end user that has their domains email on the dataserver.net system has been in touch with them.   We've send them the bounce back messages, we've sent them screen shots of the telnet not connecting but the ping responding, we've send them times when we can send, times when we can't.   We've sent them our smtp send connector log.   They still keep on asking for more logs.   They think it is a TLS issue but I'm not sure what TLS has to do with anything when sometimes we can telnet and sometimes we can't.   Does Telnet use some sort of tls that might vary?


    I dont think its related to TLS and telnet, no. Sounds like a something network related on their end.
    Saturday, June 9, 2018 8:48 PM
  • You could turn up protocol logging on the send connector and examine the logs to see more precisely whether you're connecting to them and what they're returning.  You can try doing a telnet from your server to port 25 of theirs and see if you're even getting a banner.


    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!

    Saturday, June 9, 2018 9:33 PM
  • I randomly can and cannot connect to them through telnet.  When I get the banner I consider it connected. When I can't get a banner and get the message not connected I believe it is failing.

    I do notice on my bounceback it has received from and then a IPV6 address yet the IPV6 is disabled on the exchange server nic (no check mark next to ipv6) and the firewall so I'm not sure how it is getting that.

    When I enable iPV6 we still get the delay.


    • Edited by boe_d Saturday, June 9, 2018 11:03 PM
    Saturday, June 9, 2018 11:02 PM
  • Hi,

    I noticed that you have described the issue symptom in another thread, which indicated that the issue appeared randomly.

    '441 4.4.1 Error encountered while communicating with primary target IP address: "Failed to connect. Winsock error code: 10060, Win32 error code: 10060."

    As per my experience, it should be an issue that port 25 is blocked or third party AV software or firewall block Exchange services. Please check if they are the issue causes.

    Hope it helps.

    Regards,

    Manu Meng


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

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    • Edited by Manu Meng Monday, June 11, 2018 8:23 AM
    Monday, June 11, 2018 8:07 AM
  • Hi,

    I found that you have posted a similar thread in another Exchange forum, I will merge the two threads into one.

    Thanks for your understandings.

    Regards,

    Manu Meng


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Click here to learn more. Visit the dedicated forum to share, explore and talk to experts about Microsoft Teams.

    Monday, June 11, 2018 8:30 AM
  • I still haven't figured out what is causing it to fail on a few email recipients yet but when I find out I'll post this as I've seen this for more than one exchange server now - different domains they are sending from but still no answer. I'm routing them through a smart host in the interim for domains I can't send to at the moment.
    Tuesday, June 12, 2018 9:52 PM
  • Now getting it on another client's exchange server that never had issues before.  Something very strange is going on.
    • Edited by boe_d Thursday, June 14, 2018 2:26 PM
    Thursday, June 14, 2018 2:26 PM
  • Hi,

    Is there a receive connector to relay the emails from serverdata.net? 

    Allow anonymous relay on Exchange servers

    Regards,

    Manu Meng


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Click here to learn more. Visit the dedicated forum to share, explore and talk to experts about Microsoft Teams.

    • Edited by Manu Meng Friday, June 15, 2018 9:51 AM
    Friday, June 15, 2018 9:51 AM
  • If it's "random", then I'd be thinking it's a network issue.  Could it be a misconfigured or faulty load balancer, or maybe one of your CAS nodes (if you have more than one) is bad.

    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!


    • Edited by Ed CrowleyMVP Friday, June 15, 2018 6:31 PM
    • Proposed as answer by Manu Meng Tuesday, June 19, 2018 9:50 AM
    Friday, June 15, 2018 6:31 PM
  • Hi,

    It has been a long time since you made the last post on this thread. If you could get any help from the above posts, please be free to mark them as answers,  it will be easy for other community members to find the useful one/ones.

    Thanks for your understandings!

    Regards, 

    Manu Meng


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Click here to learn more. Visit the dedicated forum to shareexplore and talk to experts about Microsoft Teams.

    • Proposed as answer by Manu Meng Wednesday, June 27, 2018 6:49 PM
    Tuesday, June 26, 2018 2:23 AM